1. Field of the Invention
The present general inventive concept relates to an image forming apparatus, and more particularly to an image forming apparatus equipped with a paper feeding unit that supplies a paper to a printing unit inside a main body.
2. Description of the Related Art
An image forming apparatus, such as a laser printer, an ink jet printer, a multi-function printer, a copying machine and the like, generally includes a main body, a printing unit mounted inside the main body, a paper feeding unit which supplies a paper to the printing unit, and a discharging unit which discharges a printed paper out of the main body. The printing unit forms an image and prints the image on the paper by using toner or ink according to a printing process.
The paper feeding unit includes a cassette type paper loading device or a tray type paper loading device, as well as a pickup roller which picks up the paper loaded on the paper loading device sheet by sheet, a feed roller which feeds the picked-up paper to the printing unit, and a register roller which aligns a front end of the transferred paper between the feed roller and the printing unit. The cassette type paper loading device is loaded with paper having the same size for automatic paper feeding, and is ideal for relatively large, routine print jobs. The tray type paper loading device is also loaded with paper, but allows a user to swiftly and manually load one or more sheets of paper of varying size as needed, which makes the tray type paper loading device ideal for relatively small, non-routine print jobs.
During the printing process, paper loaded on the paper loading device is picked up by the pickup roller, and transferred along a paper print path by the feed roller. The paper is aligned in a width direction by the register roller in the main body, and moved to the printing unit. After being printed, the paper is discharged out of the main body by the discharging unit.
However, in the paper feeding operation of a conventional image forming apparatus, the paper is picked up from the paper loading device and transferred to the printing unit by the register roller provided at the main body, which is problematic since the paper is often distorted between the paper loading device and the main body whose frames are separately provided. As such, the paper is frequently required to be realigned.
Also, because the cassette type paper loading device is removably mounted to the main body for the automatic paper feeding, the tray type paper loading device provided at the main body for the manual paper feeding and the register roller provided at the main body for the paper alignment are formed at different frames, which results in an increased number of components, increased manufacturing costs, and decreased manufacturing efficiency.